Stop watch and dial



Feb. 16 192s. 1,572,884

1 c. H. COLVIN STOP WATCH AND DIAL Filed Feb. 10. 1923 1 fi i, 1' i INVENTOR Ufa/'66,? 6, (loll in @411 WA TTORNE m Patented Feb. 16, 1926.

UNITED STATES CHARLES H. COLVIN, OF BROOKLYN, NEW YORK.

STOP WATCH AND DIAL.

Application filed February 10, 1923.

To all whom it may concern: 7

Be it known that I, CHARLES H. CoLviN, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Stop \Vatches and Dials, of which the following is a specification.

My invention relates to stop watches, and

10 more particularly to improvements in the indicating means or dials thereof.

An object of my invention is to provide in stop-watch dials improved incex means for making direct readings in terms of speed, such as miles per hour, instead of in time, thereby eliminating the necessity of using conversion tables or the making of calculations to determine the speed. Other objects and advantages will appear as the invention is disclosed.

The drawing shows a face view of a watch employing my improved dial illustrating how the watch hands cooperate therewith.

Referring to the drawing, an outer scale 21 comprises ordinary numbered graduations, which in this instance runs from 1 to 12; and this scale is for use with an hour watch hand 18 and minute hand 17 of the watch if such hands are employed. The next scale 22 is preferably divided into fifthseconds, as on an ordinary stop-watch dial; and may consist of the uniformly spaced dashes as shown. This scale 22 and the other scales to be described are for use with the sweep second hand 16 of the watch.

Another scale 23 is graduated in such a way that the mark and figure at any point denotes the speed, in units of distance per hour, such as miles per hour, which corresponds to the time in seconds per unit of distance. That is, if

1: 1 unit of distance i=time in seconds and c=speed in units of distance per hour For example, the mark and figure at the point reached by the hand 18 seconds is In other words, if the time required for the passage of one unit of distance is 2% seconds, the speed is 150 units per hour, as

Serial N0. 618,347.

for example 150 miles per hour (M. P. H.). Another scale 24 is graduated in such a way that the mark and figure at any point denote the speed, in units of distance per hour, which. corresponds to the time in seconds for a certain fraction of a unit of distance. As shown, this fraction is four tenths. That is, if

. i=.4 unit of distance if =tirne in seconds and o=speed in units of distance per hour In other words, if the time required for the passage of four-tenths unit of distance is 2% seconds, the speed is ()0 units per hour.

An example of the practical use of a stop watch with such a dial will reveal its advantages over a watch with a dial indicating in time only. Suppose the user of the watch is traveling in a railroad train and desires to determine the speed at which the train is running. He starts the watch as a mile-post is passed, and stops it as the next mile-post is reached. Referring to scale he will read his speed directly in distance units per hour, in this case in miles per hour. \Vithout my improved dial with this special scale, he would read the time in seconds, and then either would have to perform a mathematical calculation or refer to a specially prepared conversion chart, to dete "mine the speed.

Particularly for use on fast moving vehicles, such as aircraft, where it is difficult, if not impossible to make auxiliary calculations, a watch with such a dial is found to provide great advantges.

\Vhat I claim is In a stop watch, in combination, a sweep second hand scale graduated to indicate time per unit of distance; another scale concentric therewith and graduated to read directly in distance per unit of time corresponding to the. indicated time for a frac tion of a unit of distance, and a sweep second hand cooperating with either of said scales.

In testimony whereof I atiix my signature this (5th day of February 192?); in the State of New York, city of Brooklyn, and county of Kings.

CHARLES H. COLVIN. 

